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Reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in any country.
Immunological-based diagnostics provides an important tool in detecting a variety of disease conditions. This is especially the case given the specificity of components within the immune system. Notwithstanding, diagnostic outcomes can be compromised when there is non-specific immune reactivity. This can lead to false positives and potentially mis-diagnoses. There is a need to develop diagnostic assays with enhanced specificity.
One form of immunological-based diagnostic assay involves the stimulation of T-cells with antigens or mitogens in either isolated cell culture or in whole blood culture followed by the detection of effector molecules such as cytokines produced by the activated T-cells (also referred to as effector T-cells). The effector molecules are generally detected using techniques such as enzyme immunoassays, multiplex bead analysis, ELISpot and flow cytometry. Such assays are useful for detecting disease-specific T-cell responses.
In an embodiment of the above-mentioned assay, a T-cell response is measured using whole blood. Such assays are useful in the diagnosis of tuberculosis infection. However, an impediment to these types of assays is the non-specific production of effector molecules such as occurring when there is contamination by immune stimulants such as endotoxins. This is particularly the case in blood collection tubes which may be a source of endotoxin contamination. Endotoxins may also be in a blood sample itself. Such immune stimulant contaminants can lead to false positive results and potential mis-diagnoses.
An improved immune cell-mediated based assay is, therefore, needed. In particular, such assays are useful in detecting or monitoring a range of diseases and conditions in a subject with enhanced specificity.